CN116888448A - Interference insensitive littrow system for optical device structure measurement - Google Patents

Interference insensitive littrow system for optical device structure measurement Download PDF

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Publication number
CN116888448A
CN116888448A CN202180093916.4A CN202180093916A CN116888448A CN 116888448 A CN116888448 A CN 116888448A CN 202180093916 A CN202180093916 A CN 202180093916A CN 116888448 A CN116888448 A CN 116888448A
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CN
China
Prior art keywords
detector
image
optical
arm
optical path
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CN202180093916.4A
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Chinese (zh)
Inventor
孙阳阳
傅晋欣
卢多维克·葛德特
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Applied Materials Inc
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Applied Materials Inc
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/26—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/14—Measuring arrangements characterised by the use of optical techniques for measuring distance or clearance between spaced objects or spaced apertures
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/017—Head mounted
    • G02B27/0172—Head mounted characterised by optical features
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings
    • G02B5/1847—Manufacturing methods
    • G02B5/1857—Manufacturing methods using exposure or etching means, e.g. holography, photolithography, exposure to electron or ion beams
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/0101—Head-up displays characterised by optical features
    • G02B2027/0123—Head-up displays characterised by optical features comprising devices increasing the field of view
    • G02B2027/0125—Field-of-view increase by wavefront division

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

Embodiments described herein provide for measuring pitch P of an optical device structure and an orientation angle of the optical device structureIs provided. One embodiment of the system includes an optical arm with an arm coupled to an arm actuator. The optical arm includes a light source. The light source emits a light path operable to diffract into the stage. The optical arm further includes a first beam splitter and a second beam splitter positioned in the optical path. The first beam splitter directs the optical path through the first lens and the second beam splitter directs the optical path through the first dove prism and the second lens. The optical arm further includes a first detector operable to detect an optical path from the first lens and a second detector operable toAnd a second detector detecting an optical path from the second lens.

Description

Interference insensitive littrow system for optical device structure measurement
Technical Field
Embodiments of the present disclosure relate to apparatus and methods for measuring pitch P of an optical device structure and orientation angle phi of an optical device structure.
Background
Virtual reality is generally considered a computer-generated simulated environment in which a user has a distinct physical presence. The virtual reality experience may be generated in 3D form and viewed using a head-mounted display (HMD), such as glasses or other wearable display devices having a display panel proximate to the eyes as a lens to display a virtual reality environment that replaces the actual environment.
However, augmented reality enables an experience in which a user may still see the surrounding environment via the display lenses of glasses or other HMD devices, as well as the images of virtual objects that are generated to be displayed and appear as part of the environment. Augmented reality may include any type of input, such as audio and tactile input, as well as virtual images, graphics, and video of the environment that enhance or augment the user experience. As an emerging technology, augmented reality faces many challenges and design constraints.
One such challenge is displaying virtual images that are overlaid on the surrounding environment. The optics are used to assist in overlaying the image. Manufacturing optical devices can be challenging because optical devices tend to have characteristics that need to be manufactured according to specific tolerances, such as optical device structure pitch and optical device structure orientation. When measuring the optical device structure on a non-opaque substrate, the accuracy and repeatability of the known system may be reduced due to reflection and diffraction of light. Accordingly, there is a need in the art for improved apparatus and methods for measuring pitch P of an optical device structure and orientation angle phi of an optical device structure with increased accuracy and repeatability.
Disclosure of Invention
In one embodiment, a system is provided. The system includes a stage having a substrate support surface. The stage is coupled to a stage actuator configured to move the stage in a scan path and rotate the stage about an axis. The system further includes an optical arm coupled to the arm actuator, the arm actuator configured to scan the optical arm and rotate the optical arm about the axis. The optical arm includes a light source. The light source emits a light path operable to diffract into the stage. The optical arm further includes a first beam splitter and a second beam splitter positioned in the optical path. The first beam splitter directs the optical path through a first lens and the second beam splitter directs the optical path through a first dove prism (dove prism) and a second lens. The optical arm further includes a first detector operable to detect the optical path from the first lens and a second detector operable to detect the optical path from the second lens.
In another embodiment, a system is provided. The system includes a stage having a substrate support surface. The stage is coupled to a stage actuator configured to move the stage in a scan path and rotate the stage about an axis. The system further includes an optical arm coupled to the arm actuator, the arm actuator configured to scan the optical arm and rotate the optical arm about the axis. The optical arm includes a light source. The light source emits a light path operable to diffract into the stage. The optical arm further includes a daving prism positioned in the optical path. The dove prism includes an actuator for rotating the dove prism. The optical arm further includes a first beam splitter positioned in the optical path. The first beam splitter directs the optical path through the first lens and the second beam splitter directs the optical path through the second lens. The optical arm further includes a first detector operable to detect an optical path from the first lens.
In yet another embodiment, a system is provided. The system includes a stage having a substrate support surface. The stage is coupled to a stage actuator configured to move the stage in a scan path and rotate the stage about an axis. The optical arm is coupled to an arm actuator configured to scan the optical arm and rotate the optical arm about an axis. The optical arm includes a light source. The light source emits a light path operable to diffract into the stage. A first beam splitter and a second beam splitter are positioned in the optical path. The first beam splitter directs the optical path through the first lens and the second beam splitter directs the optical path through the first dove prism. The optical arm further includes a first mirror operable to direct the optical path to a second mirror, and the second mirror directs the optical path through the first lens. The optical arm further includes a first detector operable to detect an optical path from the first lens.
In yet another embodiment, a method is provided. The method includes determining a fixed beam angleAnd an initial orientation angle phi of a first region of the optical device structure of the substrate Initial initiation . The method further includes rotating the substrate to orient the initial orientation angle phi Initial initiation Positioned perpendicular to the beam to be projected onto the first area of the substrate. The method further comprises +.>Will have a certain wavelength (lambda) Laser light ) Is projected to a first area of the substrate. The method further comprises measuring a reflected beam angle of the light beam reflected by the substrate>Reflected beam angle->Obtained via the center of the symmetrical beam profile. Symmetrical with each otherThe beam profile is obtained from a combination of the first image and the second image of the light beam reflected by the substrate. The second image is rotated at a different rotation angle than the first image. The method further comprises passing the pitch equation->To determine the pitch P of the optic structure.
Drawings
So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, for the may admit to other equally effective embodiments.
FIG. 1 is a schematic diagram of a measurement system according to an embodiment.
Fig. 2A-2F are schematic diagrams of configurations of measurement systems according to some embodiments.
Fig. 3A to 3C are schematic diagrams of a detector according to an embodiment.
Fig. 3D is a schematic diagram of a dave prism according to an embodiment.
Fig. 3E is a schematic diagram of a mirror assembly according to an embodiment.
Fig. 4 is a flow chart of a method for measuring pitch P of an optical device structure and orientation angle phi of the optical device structure, according to an embodiment.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
Detailed Description
Embodiments of the present disclosure relate to apparatus and methods for measuring pitch P of an optical device structure and orientation angle phi of an optical device structure. In one embodiment, a system is provided. The system includes a stage having a substrate support surface. The stage is coupled to a stage actuator configured to move the stage in a scan path and rotate the stage about an axis. The system further includes an optical arm coupled to the arm actuator, the arm actuator configured to scan the optical arm and rotate the optical arm about the axis. The optical arm includes a light source. The light source emits a light path operable to diffract into the stage. The optical arm further includes a first beam splitter and a second beam splitter positioned in the optical path. The first beam splitter directs the optical path through the first lens and the second beam splitter directs the optical path through the first dove prism and the second lens. The optical arm further includes a first detector operable to detect the optical path from the first lens and a second detector operable to detect the optical path from the second lens.
The measurement system includes a stage, an optical arm, and a detector arm. Light projected from the optical arm is reflected from a substrate provided on the stage, and reflected light from the substrate surface is incident on the detector and the optical arm. Deflection from the optical center of the focusing lens is used to determine local non-uniformities of the optics. The method of diffracting light includes measuring a scattered light beam from a surface of a substrate and obtaining local aberrations from the measured values. The non-opaque substrate will interfere due to diffraction of light from other surfaces. The interference will be diffracted into the optical arm and the detector arm. Interferometry results in reduced accuracy and precision of the measurement results.
FIG. 1 is a schematic diagram of a measurement system 101 according to one embodiment. As shown, the measurement system 101 includes a stage 102, an optical arm 104, and a detector arm 112. The measurement system 101 is configured to diffract light projected by the optical arm 104. The light projected by the optical arm 104 is guided to the substrate 103 provided on the stage 102. Light reflected and diffracted from the substrate 103 is incident on the detector arm 112 and the optical arm 104. In one embodiment, which may be combined with other embodiments described herein, the measurement system 101 includes an optical arm 104 and a detector arm 112. In another embodiment, which may be combined with other embodiments described herein, the measurement system 101 includes only the optical arm 104.
As shown, the stage 102 includes a support surface 106 and a stage actuator 108. The stage 102 is configured to hold the substrate 103 on a support surface 106. Stage 102 is coupled to stage actuator 108. Stage actuator 108 is configured to move stage 102 in scan path 110 along the x-direction and the y-direction and rotate stage 102 about the z-axis. Stage 102 is configured to move and rotate substrate 103 during operation of measurement system 101 such that light projected from optical arm 104 is incident on different portions of substrate 103 or gratings.
The substrate 103 includes one or more optical devices 105, the one or more optical devices 105 having one or more gratings 107 of an optical device structure 109. Each of the gratings 107 includes a region of an optics structure 109. The optics structure 109 has an orientation angle phi and a pitch P. Pitch P is defined as the distance between adjacent points, such as adjacent first edges or adjacent centroids of the optic structures 109. The pitch P and orientation angle phi of the optic structures 109 of a first grating 111 of the one or more gratings 107 may be different than the pitch P and orientation angle phi of the optic structures 109 of a second grating 113. Furthermore, there may be local pitch P 'variations and local orientation angle Φ' variations of the optical device structure 109 due to local warpage or other deformation of the substrate 103. The measurement system 101 may be used to measure the pitch P and orientation angle phi of the optic structure 109 of each grating 107 of each optic 105. The substrate 103 may be a single crystal wafer of any size, such as having a radius from about 150mm to about 450 mm.
The optical arm 104, the detector arm 112, and the stage 102 are coupled to a controller 130. The controller 130 facilitates controlling and automating the methods described herein for measuring the pitch P and orientation angle phi of the optic structure 109. The controller may include a central processing unit (central processing unit, CPU) (not shown), a memory (not shown), and support circuits (or input/output (I/O)) (not shown). The CPU may be one of any form of computer processor used in an industrial environment to control various processes and hardware (e.g., motors and other hardware) and monitor processes (e.g., conveyor location and scan time). The memory (not shown) is connected to the CPU and may be readily available memory such as random access memory (random access memory, RAM). Software instructions and data may be encoded and stored in memory for instructing the CPU. A support circuit (not shown) is also connected to the CPU for supporting the processor in a known manner. The support circuits may include known caches, power supplies, clock circuits, input/output circuitry, subsystems, and the like. A program (or computer instructions) readable by the controller determines which tasks can be performed on the substrate 103. The program may be software readable by the controller and may include code to monitor and control, for example, the position of the substrate and the position of the optical arm.
Fig. 2A to 2F are schematic diagrams of configurations 200A to 200F of the measurement system 101. In embodiments where the substrate 103 is non-opaque, which may be combined with other embodiments described herein, reflection and diffraction of light from multiple surfaces of the substrate 103 will cause interference on the optical arm 104 and the detector arm 112. The interference is asymmetric, i.e., the image of the light path diffracted or reflected off the substrate 103 is not circular or substantially circular on the first detector 208 and the plurality of second detectors 218 of the optical arm 104 and the detector arm 112 as described further below. To address this problem, the measurement system 101 rotates the image using a prism (such as a dove prism). The multiple images are combined to produce a symmetrical beam, i.e., a circular beam. The centroid of the beam is determined by an image processing algorithm. The image processing algorithm may be executed at least in part by the controller 130.
Fig. 2A is a schematic diagram of a configuration 200A of the measurement system 101. Configuration 200A includes a portion 202 of a section line 201 (shown in fig. 1) on substrate 103. The substrate 103 has one or more gratings 107 of an optical device structure 109. As shown, the optical arm 104 includes a light source 204, a first beam splitter 206, a second beam splitter 212, a first detector 208, a second detector 218, a first dove prism 214, a first lens 210, and a second lens 216. The optical arm 104 communicates with a controller 130. The optical arm 104 may include an arm actuator 203. The arm actuator 203 is configured to rotate the optical arm 104 about the z-axis and scan the optical arm in the z-direction. The optical arm 104 may be fixed while the measurements are performed.
The first beam splitter 206 is positioned adjacent the light source 204 in a first optical path 220. In one embodiment, which may be combined with other embodiments described herein, the first optical path 220 has a circular or substantially circular cross-section. The light beam described herein may be a laser beam. According to one embodiment, the light source 204 is operable to project light along the first light path 220 at a beam angle θ (shown in fig. 1) to the substrate 103. The light source 204 is operable to project a collimated beam of light. The first optical path 220 is incident on the substrate 103 and diffracts the second optical path 222 back to the optical arm 104. The optical arm 104 transmits the first optical path 220 such that light may be diffracted by the substrate 103 and form the second optical path 222. In one embodiment, which may be combined with other embodiments described herein, the second optical path 222 is first order diffraction. The second optical path 222 is split into a second optical path 222A and a second optical path 222B by the second beam splitter 212.
The first beam splitter 206 is operable to deflect the second optical path 222A diffracted by the substrate 103 to the first detector 208. The first lens 210 is positioned between the first beam splitter 206 and the first detector 208. The first lens 210 is configured to focus the second optical path 222A onto the first detector 208. The first image of the second light path 222A is projected on the first detector 208. The first detector 208 is any optical means used in the art for detecting light, such as a charge-coupled device (CCD) array or an active pixel sensor (complementary metal oxide semiconductor (CMOS) array).
The second beam splitter 212 is operable to deflect the second light path 222B diffracted by the substrate 103 to the second detector 218. The second lens 216 is positioned between the second beam splitter 212 and the second detector 218. The second lens 216 is configured to focus the second light path 222B onto the second detector 218. The second light path 222B passes through the first dove prism 214 before contacting the second detector 218. The first doffer prism 214 rotates the image of the second light path 222B on the second detector 218. Thus, a second image of the second light path 222B is projected on the second detector 218. The rotation angle of the second image is different from that of the first image. The first doffer prism 214 is operable to rotate the second image at any angle. In one embodiment, which may be combined with other embodiments described herein, the second image is rotated 180 ° relative to the first image. The second detector 218 is any optical device used in the art for detecting light, such as a CCD array or a CMOS array.
Fig. 2B is a schematic diagram of a configuration 200B of the measurement system 101. Configuration 200B includes a portion 202 of a section line 201 (shown in fig. 1) on substrate 103. The substrate 103 has one or more gratings 107 of an optical device structure 109. As shown, the optical arm 104 includes a light source 204, a first beam splitter 206, second beam splitters 212a, …, 212n (collectively, "a plurality of second beam splitters 212"), a first detector 208, second detectors 218a, …, 128n (collectively, "a plurality of second detectors 218"), first daffodies 214a, …, 214n (collectively, "a plurality of first daffodies 214"), a first lens 210, and second lenses 216a, …, 216n (collectively, "a plurality of second lenses 216"). The optical arm 104 communicates with a controller 130. The optical arm 104 may include an arm actuator 203. The arm actuator 203 is configured to rotate the optical arm 104 about the z-axis and scan the optical arm in the z-direction. The optical arm 104 may be fixed while the measurements are performed.
The first beam splitter 206 is positioned adjacent the light source 204 in a first optical path 220. According to one embodiment, the light source 204 is operable to project light along the first light path 220 at a beam angle θ (shown in fig. 1) to the substrate 103. The first optical path 220 is incident on the substrate 103 and projects the second optical path 222 to the optical arm 104. The optical arm 104 transmits the first optical path 220 such that light may be diffracted by the substrate 103 and form the second optical path 222. The second optical path 222 is split into second optical paths 222a, …, 222n (collectively, "plurality of second optical paths 222") by the plurality of second beam splitters 212.
The first beam splitter 206 is operable to deflect the second optical path 222A diffracted by the substrate 103 to the first detector 208. The first lens 210 is positioned between the first beam splitter 206 and the first detector 208. The first lens 210 is configured to focus the second optical path 222A onto the first detector 208. The first image of the second light path 222A is projected on the first detector 208.
The plurality of second beam splitters 212 are operable to deflect the plurality of second light paths 222B, …, 222n diffracted by the substrate 103 to the plurality of second detectors 218. A plurality of second lenses 216 are positioned between the plurality of second beam splitters 212 and the plurality of second detectors 218. The plurality of second lenses 216 are configured to focus the second light paths 222B, …, 212n onto the plurality of second detectors 218. The second light paths 222B, …, 222n pass through the plurality of first dove prisms 214 before contacting the plurality of second detectors 218. The plurality of first dove prisms 214 rotate the image of each of the second light paths 222B, …, 222n on the plurality of second detectors 218. Thus, the second image from each of the second light paths 222B, …, 222n is diffracted on the plurality of second detectors 218. The plurality of second images are rotated at an angle different from the first image. In one embodiment, which may be combined with other embodiments described herein, the two second images are rotated 120 ° relative to the first image such that the second images are at 120 ° and 240 °. In another embodiment, which may be combined with other embodiments described herein, each of the plurality of second images is rotated 360 °/n relative to the first image, where n is the number of images detected by the plurality of second detectors 218.
Fig. 2C is a schematic diagram of a configuration 200C of the measurement system 101. Configuration 200C includes a portion 202 of section line 201 on substrate 103. The substrate 103 has one or more gratings 107 of an optical device structure 109. As shown, the optical arm 104 includes a light source 204, a first beam splitter 206, a second beam splitter 212a, …, 212n (collectively, "a plurality of second beam splitters 212"), a first detector 208, a second detector 218a, …, 128n (collectively, "a plurality of second detectors 218"), a first dove prism 214a, …, 214n (collectively, "a plurality of first dove prisms 214"), a second dove prism 224, a first lens 210, and a second lens 216a, …, 216n (collectively, "a plurality of second lenses 216"). The optical arm 104 is coupled to a controller 130. The optical arm 104 may include an arm actuator 203, and the arm actuator 203 is configured to rotate the optical arm 104 about a z-axis and scan the optical arm in a z-direction. The optical arm 104 may be fixed while the measurements are performed.
The first beam splitter 206 is positioned adjacent the light source 204 in a first optical path 220. According to one embodiment, the light source 204 is operable to project light along the first light path 220 at a beam angle θ (shown in fig. 1) to the substrate 103. The first optical path 220 is incident on the substrate 103 and diffracts the second optical path 222 to the optical arm 104. The optical arm 104 transmits the first optical path 220 such that light may be diffracted by the substrate 103 and form the second optical path 222. The second optical path 222 is split by the second beam splitter 212, i.e., into a plurality of second optical paths 222A, 222B … … n.
The first beam splitter 206 is operable to deflect the second optical path 222A diffracted by the substrate 103 to the first detector 208. The first lens 210 is positioned between the first beam splitter 206 and the first detector 208. The first lens 210 is configured to focus the second optical path 222A onto the first detector 208. The second optical path 222A passes through a second dove prism 224 before contacting the first detector 208. The second doffer prism 224 rotates the image of the second light path 222A on the first detector 208. Thus, the first image of the second light path 222A is projected on the first detector 208. The first image of the second optical path 22A may be rotated to any He Jiaodu by the second doffer prism 224.
The plurality of second beam splitters 212 are operable to deflect the plurality of second light paths 222B, …, 222n diffracted by the substrate 103 to the plurality of second detectors 218. A plurality of second lenses 216 are positioned between the plurality of second beam splitters 212 and the plurality of second detectors 218. The plurality of second lenses 216 are configured to focus the second light paths 222B, …, 212n onto the plurality of second detectors 218. The second light paths 222B, …, 222n pass through the plurality of first dove prisms 214 before contacting the plurality of second detectors 218. The plurality of first dove prisms 214 rotate the image of each of the second light paths 222B, …, 222n on the plurality of second detectors 218. Thus, a second image of each of the second light paths 222B, …, 222n is projected onto the plurality of second detectors 218. The plurality of second images are rotated at an angle different from the first image. In one embodiment, which may be combined with other embodiments described herein, the two second images are rotated 120 ° relative to the first image such that the second images are at 120 ° and 240 °. In another embodiment, which may be combined with other embodiments described herein, each of the plurality of second images is rotated 360 °/n relative to the first image, where n is the number of images detected by the second detector 218.
Fig. 2D is a schematic diagram of a configuration 200D of the measurement system 101. Configuration 200D includes a portion 202 of section line 201 on substrate 103. The substrate 103 has one or more gratings 107 of an optical device structure 109. As shown, the optical arm 104 includes a light source 204, a first beam splitter 206, a first detector 208, a first dove prism 214, and a first lens 210. The optical arm 104 is coupled to a controller 130. The optical arm 104 may include an arm actuator 203, and the arm actuator 203 is configured to rotate the optical arm 104 about a z-axis and scan the optical arm in a z-direction. The optical arm 104 may be fixed while the measurements are performed.
The first beam splitter 206 is positioned adjacent the light source 204 in a first optical path 220. In one embodiment, which may be combined with other embodiments described herein, the first optical path 220 has a circular or substantially circular cross-section. According to one embodiment, the light source 204 is operable to project light along the first light path 220 at a beam angle θ (shown in fig. 1) to the substrate 103. The first optical path 220 is incident on the substrate 103 and diffracts the second optical path 222 to the optical arm 104. The optical arm 104 transmits the first optical path 220 such that light may be diffracted by the substrate 103 and form the second optical path 222. In one embodiment, which may be combined with other embodiments described herein, the second optical path 222 is first order diffraction.
The first beam splitter 206 is operable to deflect the second optical path 222 diffracted by the substrate 103 to the first detector 208. The first lens 210 is positioned between the first beam splitter 206 and the first detector 208. The first lens 210 is configured to focus the second optical path 222 onto the first detector 208. The first image of the second light path 222A is projected on the first detector 208. The second optical path 222 passes through the first dove prism 214 before contacting the first beam splitter 206. The first doffer prism 214 rotates the image of the second light path 222 on the first detector 208. Thus, the first image of the second light path 222 is diffracted on the first detector 208. In one embodiment, which may be combined with other embodiments described herein, the first dove prism 214 is coupled to a dove prism actuator 226. The doffer prism actuator is operable to rotate the first doffer prism 214 such that a plurality of images (such as a first image and a plurality of second images) of the second optical path 222 can be projected onto the first detector 208. In one embodiment, which may be combined with other embodiments described herein, the plurality of second images are at 90 ° relative to the first image such that each of the second images is at 90 °, 180 ° and 270 °. In another embodiment, which may be combined with other embodiments described herein, each of the plurality of second images is rotated 360 °/n relative to the first image, where n is the number of images detected by the second detector 218.
Fig. 2E is a schematic diagram of a configuration 200E of the measurement system 101. Configuration 200E includes a portion 202 of section line 201 on substrate 103. The substrate 103 has one or more gratings 107 of an optical device structure 109. As shown, the optical arm 104 includes a light source 204, a first beam splitter 206, a second beam splitter 212, a first detector 208, a first doffer prism 214, a first mirror 228, a second mirror 230, and a first lens 210. The optical arm 104 is coupled to a controller 130. The optical arm 104 may include an arm actuator 203, and the arm actuator 203 is configured to rotate the optical arm 104 about a z-axis and scan the optical arm in a z-direction. The optical arm 104 may be fixed while the measurements are performed.
The first beam splitter 206 is positioned adjacent the light source 204 in a first optical path 220. In one embodiment, which may be combined with other embodiments described herein, the first optical path 220 has a circular or substantially circular cross-section. The light beam described herein may be a laser beam. According to one embodiment, the light source 204 is operable to project light along the first light path 220 at a beam angle θ (shown in fig. 1) to the substrate 103. The first optical path 220 is incident on the substrate 103 and diffracts the second optical path 222 to the optical arm 104. The optical arm 104 transmits the first optical path 220 such that light may be diffracted by the substrate 103 and form the second optical path 222. In one embodiment, which may be combined with other embodiments described herein, the second optical path 222 is first order diffraction. The second optical path 222 is split by the second beam splitter 212, i.e., into a second optical path 222A and a second optical path 222B.
The first beam splitter 206 is operable to deflect the second optical path 222A diffracted by the substrate 103 to the first detector 208. The first lens 210 is positioned between the first beam splitter 206 and the first detector 208. The first lens 210 is configured to focus the second optical path 222A onto the first detector 208. The first image of the second light path 222A is projected on the first detector 208.
The second beam splitter 212 is operable to deflect the second optical path 222B diffracted by the substrate 103 to the first mirror 228. The second light path 222B reflects from the first mirror 228 to the second mirror 230. The second light path 222B diffracts to the first lens 210. The first lens 210 is configured to focus the second optical path 222B onto the first detector 208. The second light path 222B passes through the first dove prism 214 before contacting the first mirror 228. The first doffer prism 214 rotates the image of the second light path 222B on the first detector 208. Thus, the second image of the second light path 222B is projected on the first detector 208 such that the first detector 208 detects the first image and the second image. In one embodiment, which may be combined with other embodiments described herein, the second image is rotated 180 ° relative to the first image.
Fig. 2F is a schematic diagram of a configuration 200F of the measurement system 101. Configuration 200F includes portion 202 of section line 201 on substrate 103. The substrate 103 has one or more gratings 107 of an optical device structure 109.
As shown, the optical arm 104 includes a light source 204, a first beam splitter 206, a second beam splitter 212, a first detector 208, a second detector 218, a first dove prism 214, a first lens 210, and a second lens 216. The optical arm 104 is coupled to a controller 130. The optical arm 104 may include an arm actuator 203, and the arm actuator 203 is configured to rotate the optical arm 104 about a z-axis and scan the optical arm in a z-direction. The optical arm 104 may be fixed while the measurements are performed. Configuration 200F illustrates optical arm 104 of configuration 200A of measurement system 101. Although the optical arm 104 of configuration 200A is illustrated in fig. 2F, any of the optical arms 104 of configurations 200A-200E may be included in configuration 200F.
Configuration 200 further includes detector arm 112. The detector arm 112 is operable to measure the reflected light path 234. The reflected light path 234 is a direct reflection of the first light path 220. The first optical path 220 is incident on the substrate 103 and diffracts the reflected optical path 234 to the detector arm 112.
In one embodiment, which may be combined with other embodiments described herein, the detector arm 112 includes a second beam splitter 212, a first detector 208, a second detector 218, a first dove prism 214, a first lens 210, and a second lens 216. The detector arm 112 may include a detector arm actuator 205, and the detector arm actuator 205 is configured to rotate the detector arm 112 about the z-axis and scan the optical arm in the z-direction. The detector arm 112 may be fixed while the measurements are performed. The detector arm 112 may have a similar configuration to the optical arm 104 of configurations 200A-200E.
The reflected light path 234 is split by the second beam splitter 212, i.e., split into a reflected light path 234A and a reflected light path 234B. The reflected light path 234A diffracted by the substrate 103 diffracts to the first detector 208. The first lens 210 is positioned between the first beam splitter 206 and the first detector 208. The first lens 210 is configured to focus the reflected light path 234A onto the first detector 208. The first image of the reflected light path 234A is projected on the first detector 208. The first detector 208 is any optical device used in the art for detecting light, such as a CCD array or a CMOS array.
The second beam splitter 212 is operable to deflect the reflected light path 234B diffracted by the substrate 103 to the second detector 218. The second lens 216 is positioned between the second beam splitter 212 and the second detector 218. The second lens 216 is configured to focus the reflected light path 234B onto the second detector 218. The reflected light path 234B passes through the first dove prism 214 before contacting the second detector 218. The first doffer prism 214 rotates the image of the reflected light path 234B on the second detector 218. Thus, a second image of the reflected light path 234B is projected on the second detector 218. The second detector 218 is any optical device used in the art for detecting light, such as a CCD array or a CMOS array.
Fig. 3A illustrates a detector 302 that is a position sensitive detector 301A (i.e., a lateral sensor) according to one embodiment. The detector 302 may be any detector, such as the first detector 208 and the second detector 218 of the configurations 200A-200F. Fig. 3B illustrates a detector 302 as a quadrant sensor 301B, according to one embodiment. Fig. 3C illustrates a detector 302 as an image sensor array 301C (such as a CCD array or CMOS array) according to some embodiments.
Fig. 3D is a schematic diagram of a doffer prism 304, such as first doffer prism 214 and second doffer prism 224. The optical path 306 (such as the plurality of second optical paths 222A, 222B, …, 222n and the reflected optical path 234B) may pass through the daving prism 304. The light path 306 travels through the dove prism 304 such that the light path 306 rotates as desired.
Fig. 3E is a schematic diagram of the mirror assembly 308. In one embodiment, which may be combined with other embodiments described herein, the mirror assembly 308 may replace the dave prism 304. The mirror assembly 308 includes a plurality of mirrors 310. The optical path 306 travels through the mirror assembly 308 such that the optical path 306 rotates by reflection between the plurality of mirrors 310.
Fig. 4 is a flow chart of a method 400 for measuring the pitch P of the optic structures 109 and the orientation angle phi of the optic structures 109. To facilitate explanation, the method 400 will be described with reference to the measurement system 101 of fig. 1 and the first configuration 200A of the measurement system 101 shown in fig. 2A. The controller 130 is operable to facilitate the operation of the method 400.
At operation 401, a fixed beam angle of a plurality of optic structures 109 is determinedAnd an initial orientation angle phi Initial initiation . Fixed beam angle->Is the initial angle of the beam to be projected onto the substrate 103. Initial orientation angle phi Initial initiation Is the desired orientation angle for each of the plurality of optic structures 109. In one embodiment, which may be combined with other embodiments described herein, the beam angle is fixed prior to manufacturing the optical device 105>And initial orientationAngle phi Initial initiation Is determined by the predetermined specifications of the optics structure 109 of each grating 107 of the optics 105 on the substrate 103. In a further embodiment, which can be combined with the other embodiments described herein, the beam angle is fixed +.>And an initial orientation angle phi Initial initiation Is determined by estimation.
At operation 402, the stage 102 is rotated about the z-axis to rotate the initial orientation angle φ of the optics structure 109 of the first region 115 Initial initiation Positioned perpendicular to the beam to be projected onto the first region 115 of the substrate 103. The first region 115 corresponds to a first region of the optical device structure 109 to be measured. At operation 403, a light having a wavelength (λ) from the optical arm 104 Laser light ) At a fixed beam angleProjected onto the substrate 103.
At operation 404, a reflected beam angle of the first order mode beam (R_1st) reflected by the optics structure 109 is determinedIn one embodiment, which may be combined with other embodiments described herein, the method 400 utilizes the configuration 200A of the optical arm 104 of the measurement system 101. The first image of the second light path 222A is detected by the first detector 208. The second image of the second light path 222B is detected by the second detector 218. The second image is rotated by the first doffer prism 214 such that the second image is rotated 180 ° relative to the first image.
In another embodiment, which may be combined with other embodiments described herein, the method 400 utilizes the configuration 200B of the optical arm 104 of the measurement system 101. The first image of the second light path 222A is detected by the first detector 208. A plurality of second images of the second light paths 222B, …, 222n are detected by a plurality of second detectors 218. Each of the plurality of second images is rotated 360 °/n relative to the first image, where n is the number of images detected by the second detector 218.
In another embodiment, which may be combined with other embodiments described herein, the method 400 utilizes the configuration 200C of the optical arm 104 of the measurement system 101. The first image of the second light path 222A is detected by the first detector 208. The first image is rotated by the second doffer prism 224. A plurality of second images of the second light paths 222B, …, 222n are detected by a plurality of second detectors 218. Each of the plurality of second images is rotated 360 °/n relative to the first image, where n is the number of images detected by the second detector 218.
In another embodiment, which may be combined with other embodiments described herein, the method 400 utilizes the configuration 200D of the optical arm 104 of the measurement system 101. The first doffer prism 214 includes a doffer prism actuator 226 that rotates the first doffer prism 214. The plurality of images, such as the first image and the plurality of second images, are detected by the first detector 208. Each of the plurality of second images is rotated 360 °/n relative to the first image, where n is the number of images detected by the first detector 208.
In another embodiment, which may be combined with other embodiments described herein, the method 400 utilizes the configuration 200E of the optical arm 104 of the measurement system 101. The first image of the second light path 222A is detected by the first detector 208. The second image of the second light path 222B is detected by the second detector 218. The second image is rotated by the first doffer prism 214 and reflected by the first mirror 228 and the second mirror 230 such that the second image is rotated 180 ° relative to the first image.
In another embodiment, which may be combined with other embodiments described herein, the method 400 utilizes the configuration 200F of the optical arm 104 and the detector arm 112 of the measurement system 101. The optical arm 104 may be any of the configurations 200A-200E. The first detector 208 of the detector arm 112 may detect a first image of the reflected light path 234A. A second image of the reflected light path 234B is detected by the second detector 218. The second image is rotated by the first doffer prism 214 and reflected by the first mirror 228 and the second mirror 230 such that the second image is rotated 180 ° relative to the first image.
In one embodiment, which may be combined with other embodiments described herein, at least the first image and the second image are combined to produce a symmetrical beam profile. In another embodiment, which may be combined with other embodiments described herein, the plurality of second images are combined with the first image to produce a symmetrical beam profile. An image processing algorithm is applied (via image processing software) to the symmetric beam profile to calculate the center of the symmetric beam profile. The image processing algorithm is at least partially executed by the controller 130.
Utilizing the measurement system 101 described herein allows combining multiple images to determine the center of a symmetric beam profile. When using a non-opaque substrate 103, interference due to multi-surface reflection may occur, which will change the intensity distribution projected to the detector. The measurement system 101 allows to project a second image rotated at a different angle to a plurality of second detectors. The rotated second image compensates for the asymmetric interference by allowing the center of the symmetric beam profile to be reliably determined with the additional image. By combining the second image with the first image, the center of the symmetrical beam profile is reliably obtained despite the interference.
Reflected beam angle of first order mode beam (R_1st) reflected by optics structure 109Is calculated based on the center of the symmetric beam profile. A final orientation angle phi corresponding to the orientation angle phi of the optical device structure 109 Final result Is calculated based on the center of the symmetric beam profile.
In one embodiment, which may be combined with other embodiments described herein, during operations 401-404, detector arm 112 having first detector 208 and second detector 218 measures a zero order mode beam (r—0), such as reflected light path 234 (shown in fig. 2F) reflected by optics structure 109, to determine a retro-reflected beam angleAngle of the reflected beam>Angle +.>The comparison is made to take into account the warpage of the substrate 103.
At operation 405, the equation is passed throughThe pitch P is determined. At operation 406, the stage 102 is scanned along the scan path 110, and operations 401 through 405 are repeated for subsequent regions of the one or more gratings 107 of the one or more optical devices 105.
In summary, provided herein are apparatus and methods for measuring pitch P of an optical device structure and orientation angle phi of an optical device structure. The apparatus and method provide a more accurate reading of pitch P and orientation angle phi by combining the first image and the second image in a measurement system. The combination of the first image and the second image improves the accuracy and repeatability of the measurement by: asymmetric interference is compensated by allowing the center of the symmetric beam profile to be reliably determined with additional images. The apparatus and methods described herein take into account interference when measuring non-opaque substrates.
While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims (20)

1. A system, comprising:
a stage having a substrate support surface, the stage coupled to a stage actuator configured to move the stage in a scan path and rotate the stage about an axis; and
an optical arm coupled to an arm actuator configured to scan the optical arm and rotate the optical arm about the axis, the optical arm having:
a light source that emits a light path operable to project onto a substrate disposed on the substrate support surface;
a first beam splitter and a second beam splitter, the first beam splitter and the second beam splitter positioned in the optical path;
a first dove prism;
a first lens and a second lens, wherein the first beam splitter is configured to direct the optical path through the first lens and the second beam splitter is configured to direct the optical path through the first darff prism and the second lens;
A first detector operable to detect the optical path from the first lens; and
a second detector operable to detect the optical path from the second lens.
2. The system of claim 1, further comprising:
an additional second beam splitter that directs the optical path through an additional first dav prism and an additional second lens; and
additional second detectors, each second detector being operable to detect the optical paths projected from each of the additional second lenses, each of the additional second detectors being configured to detect a second image projected from each of the additional second lenses.
3. The system of claim 2, further comprising a second dariff prism positioned in the optical path between the first lens and the first detector.
4. The system of claim 3, wherein the second dariff prism is configured to rotate a first image projected to the first detector, wherein the first image is rotated to a different angle than each of the second images.
5. The system of claim 1, wherein the first detector is configured to detect a first image projected from the first lens.
6. The system of claim 5, wherein the second detector is configured to detect a second image projected from the second lens.
7. The system of claim 6, wherein the first doffer prism is configured to rotate the second image projected to the second detector, wherein the second image is rotated to a different angle than the first image.
8. The system of claim 7, wherein the second image is rotated 180 ° relative to the first image.
9. The system of claim 6, further comprising a controller in communication with the first detector and the second detector, wherein the controller is configured to combine the first image and the second image to form a symmetric beam profile, the controller configured to execute image processing software to determine a center of the symmetric beam profile.
10. The system of claim 1, further comprising a detector arm coupled to a detector arm actuator configured to scan the detector arm and rotate the detector arm about the axis, the detector arm having:
A third beam splitter and a fourth beam splitter positioned in the optical path, the third beam splitter directing the optical path through a third lens, the fourth beam splitter directing the optical path through a second dove prism and a fourth lens;
a third detector operable to detect the optical path from the third lens; and
a fourth detector operable to detect the optical path from the fourth lens.
11. The system of claim 1, wherein the first detector and the second detector are one of a lateral sensor, a quadrant inspector, or an image sensor array.
12. A system, comprising:
a stage having a substrate support surface, the stage coupled to a stage actuator configured to move the stage in a scan path and rotate the stage about an axis;
an optical arm coupled to an arm actuator configured to scan the optical arm and rotate the optical arm about the axis, the optical arm having:
A light source that emits a light path operable to project onto a substrate disposed on the substrate support surface;
a dove prism positioned in the optical path between the light source and the substrate support surface;
a first beam splitter positioned in the optical path;
a first lens, wherein the first beam splitter is configured to direct the optical path through the first lens; and
a first detector operable to detect the optical path projected from the first lens.
13. The system of claim 12, wherein the dave prism is coupled to an actuator configured to rotate the dave prism.
14. The system of claim 13, wherein the first detector is configured to detect a first image and a plurality of second images projected from the first lens.
15. The system of claim 14, wherein the dave prism is configured to rotate such that the plurality of second images projected onto the first detector are each rotated to an angle different from the first image.
16. The system of claim 12, wherein the first detector is one of a lateral sensor, a quadrant inspector, or an image sensor array.
17. A method comprising the steps of:
determining a fixed beam angle θ of a light source 0 And an initial orientation angle phi of a first region of the optical device structure of the substrate Initial initiation ；
Rotating the substrate to set the initial orientation angle phi Initial initiation Positioned perpendicular to the beam at the fixed beam angle theta 0 An optical path projected to the first region of the substrate;
at the fixed beam angle theta 0 Will have a wavelength (lambda) Laser light ) Is projected onto the first region of the substrate, the optical path diffracting from the optics structure to a beam splitter, the beam splitter directing a first portion of the optical path to a first detector and a second portion of the optical path to a second detector;
detecting a first image from the first portion of the optical path with the first detector; and
detecting a second image from the second portion of the optical path with the second detector, wherein the second image is rotated to a different angle than the first image.
18. The method of claim 17, further comprising the step of: measuring a voltage applied to the substrateReflected beam angle θ of the reflected light path Reflection of The reflected beam angle theta Reflection of Derived from the center of a symmetrical beam profile obtained by combining a first image of the optical path reflected by the substrate and a second image rotated at a different rotation angle than the first image.
19. The method of claim 18, further comprising the step of: by pitch equation p=λ Laser light /(sinθ 0 +sinθ Reflection of ) To determine the pitch P of the optic structure.
20. The method of claim 19, further comprising the step of: an additional second image projected onto the second detector is detected.
CN202180093916.4A 2021-01-06 2021-12-20 Interference insensitive littrow system for optical device structure measurement Pending CN116888448A (en)

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